Sheet conveying apparatus and original document processing apparatus

ABSTRACT

A sheet conveying apparatus has a conveyor for conveying a sheet to a prescribed position, a pair of reverse-discharge rotating members capable of rotating forward and reverse for feeding the sheet to the conveyor by switchback and an electricity removal unit for removing electricity from the conveyed sheet. The switchback serves to feed a sheet having a maximum conveyable length from the pair of reverse-discharge rotating members to the conveyor and the electricity removal unit is arranged downstream in a sheet discharging direction from a cross over position for a front edge of the sheet and a back edge of the sheet during discharge of the sheet, and at a downstream side to the sheet discharging direction of the pair of reverse-discharge rotating members.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a sheet conveying apparatus for a printer,facsimile or the like and an image reading apparatus thereof.

2. Description of Related Art

Conventionally, among an image reading apparatus such as a digitalcopier, a printer, or a facsimile, there is an original documentprocessing apparatus, such as a sheet conveying apparatus, beingopenable-closable against an original document table for automaticallyfeeding an original document (a sheet) to an image reading apparatus.The image reading apparatus serves to read an image of the originaldocument by performing exposure upon the original document automaticallyfed from the original document processing apparatus.

Further, in respect of a discharge portion of the original documentprocessing apparatus, there is one where the sheet is directlydischarged after a reading process of an image, and the other is wherean original document is switched back after an image of a front side ofa double-sided original document is read, and is then further subject toreading of the backside, and is once again switched back and conveyed tobe discharged.

A conventional original document processing apparatus having theforegoing structure is shown in FIG. 5. In the drawing, the dischargeportion of the original document processing apparatus is structured witha pair of reverse-discharge rollers 201 a, 201 b for performing aswitchback operation and for performing a discharging operation.

During the discharging operation of the original document processingapparatus, the original document is conveyed with a prescribed speed bythe conveying portion 203, and then, an image is read at a readingposition 204, and then, the original document is guided to a dischargeportion 202 by a C-guide 207, and then, the original document isdischarged to a discharge tray 205 by a pair of reverse-dischargerollers 201 a, 201 b.

During the switchback operation of the original document processingapparatus, after the original document is conveyed with a prescribedspeed by the conveying portion 203 in the same manner as the above, andafter an image is read at a reading position 204, the original documentis passed through a primary conveying path R1 and is guided to thedischarge portion 202 by a flapper 209 and by the C-guide 207. Then,after a rear edge of the original document passes a reverse-dischargesensor, the pair of reverse-discharge rollers 201 a, 201 b startsreversal while nipping the original document, and with the work of theflapper 209, the original document is conveyed once again to theconveying portion 203 so as to pass a conveying path R2.

With such structure, when a path of the conveying portion 203 isshortened for size reducing the original document processing apparatus,an original document having a maximum conveyable length would becomecrossed over at the discharge portion 202 during the switchbackconveyance process; accordingly there is an original document processingapparatus where the pair of reverse-discharge rollers 201 a, 201 b areseparably structured.

With such structure, when reading the first surface, the pair ofreverse-discharge rollers 201 a, 201 b are separated before starting theoriginal document reading process. During this process, thereverse-discharge roller 201 a serves a driving roller and starts todrive in an original document discharge direction. After the reading ofthe first reverse discharge rollers 201 a, 201 b nips the originaldocument, and then, after the rear edge of the original document passesthe reverse discharge sensor 208, the pair of reverse discharge rollers201 a, 201 b drives in reverse for conveying the original document tothe conveying portion 203.

After the switchback where the original document is delivered to theconveying portion 203 by the discharge portion 202, the pair ofreverse-discharge rollers 201 a, 201 b separates and momentarily ceasesdriving, and then, when the conveying portion 203 delivers the originaldocument until the front edge of the original document reaches thereading position 204 for reading the second surface, thereverse-discharge roller 201 a starts driving in the original documentdischarge direction in the same manner as the reading of the firstsurface.

After the reading of the second surface, the pair of reverse-dischargerollers 201 a, 201 b nips and conveys the original document and onceagain repeats reversal in means to sort the order of the dischargedoriginal document and finally completes the reading operation.

During the reading operation, when the original document processingapparatus conveys an original document having a maximum conveyablelength, the pair of reverse-discharge rollers 201 a, 201 b is requiredto be separated since the front edge of the original document havingbeen switchback conveyed again to the discharge portion 202 and the backedge of the original document being in the midst of switchbackconveyance would cross over at the discharge portion 202.

Further, an electricity removal needle 206 is normally disposed near thepair of reverse-discharge rollers 201 a, 201 b, and serves to removeelectric charge of the original document and prevent the matchingtrouble of the original document caused by electrification.

However, the conventional original document processing apparatus had thefollowing problems during the discharge operation and the switchbackoperation.

When the path of the conveying portion 203 is shortened for sizereduction of the apparatus where the original document processingapparatus conveys an original document having a maximum conveyablelength, the front edge of the original document and the back edge of theoriginal document would cross over at the discharge portion 202 duringthe switchback conveyance. Therefore, the pair of reverse-dischargerollers 201 a, 201 b are separably structured so that the pair ofreverse-discharge rollers 201 a, 201 b would not affect the front edgeof the original document and the back edge of the original documentbeing conveyed in a different direction, respectively.

In such case, the electricity removal needle 206 arranged nearby thepair of reverse-discharge rollers 201 a, 201 b makes contact with theoriginal document and serves to remove electricity, nevertheless, duringa switchback conveyance of the original document having maximum length,one end portion would overlap with the other end portion causing theoriginal document to be discharged without having the front edge of theoriginal document to contact with the electricity removal needle 206 andresult to a risk of stacking trouble caused by electrification, due tothe fact that the front edge of the original document is released by anipping portion of the pair of reverse-discharge rollers 201 a, 201 band discharged while the rear edge of the original document being in themidst of switchback conveyance would still be left at the dischargeportion 202.

It is an object of this invention to solve the foregoing problems byproviding a sheet conveying apparatus capable of steadily removingelectricity from a sheet even during a switchback conveyance and toprovide an image reading apparatus thereof.

SUMMARY OF THE INVENTION

In means to solve the foregoing problems, this invention proposes asheet conveying apparatus comprising: a conveying means for conveying asheet to a prescribed position; a pair of reverse-discharge rotatingmembers capable of rotating forward and reverse for feeding the sheet tothe conveying means by switchback; and an electricity removal means forremoving electricity from the conveyed sheet; wherein the switchbackserves to feed a sheet having a maximum conveyable length from the pairof reverse-discharge rotating members to the conveying means; andwherein the electricity removal means is arranged downstream in a sheetdischarging direction from a cross over position for a front edge of thesheet and a back edge o the sheet during discharge of the sheet afterhaving passed the prescribed position, and passed the pair ofreverse-discharge rotating members again.

Owing to this invention, removal of electricity for a dischargedoriginal document could steadily be performed and stacking performancecould be improved by means of feeding a sheet of a maximum conveyablelength to a conveying means from a pair of reverse-discharge rotatingmembers by switchback, and arranging an electricity removal means forremoving electricity at a position downstream in the sheet dischargingdirection from the cross over position of the front edge and the rearedge of the original document when being discharged after passing aprescribed position and passing the pair of reverse-discharge rotatingmembers once again.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the invention are apparentto those skilled in the art from the following preferred embodimentsthereof when considered in conjunction with the accompanied drawings, inwhich:

FIG. 1 is a schematic explanatory view showing an image readingapparatus of an embodiment for this invention;

FIG. 2 is a cross sectional explanatory view showing original documentprocessing apparatus of an embodiment for this invention;

FIG. 3 is an explanatory view showing a switchback conveyance path of anembodiment for this invention;

FIG. 4 is a cross sectional explanatory view showing an originaldocument processing apparatus of an embodiment for this invention; and

FIG. 5 is a cross sectional explanatory view showing a conventionaloriginal document processing apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An original document processing apparatus being an exemplary sheetconveying apparatus of this invention will be used for explaininghereinafter the structures of an original document processing apparatusand an image reading apparatus with reference to FIG. 1 through FIG. 3.FIG. 1 is a schematic explanatory view showing an image readingapparatus; FIG. 2 is a cross-sectional explanatory view showing anoriginal document processing apparatus; and FIG. 3 is an explanatoryview of a switchback conveying path.

(Overall Structure)

As for an outlined description, in a manner shown in FIG. 1, theoriginal document processing apparatus 101 is arranged with an imagereading apparatus 102 positioned above a hinge portion 104 disposedtherebetween, and conveys an original document to a reading position eof the image reading apparatus 102. The image reading apparatus 102 hasa small platen glass 8 and a large platen glass 15, a jump stand 10, andan exposure apparatus 103, in which the exposure apparatus 103 performsexposure upon the original document conveyed from the original documentprocessing apparatus 101.

Next, a conveying method of a one-side original document will bedescribed with reference to FIG. 2. An original document stackingportion A has a stacking tray 1, in which the original document isstacked upon the stacking tray 1.

In respect of an original document feeding portion B, a pickup roller 2draws in a bundle of original documents stacked on the stacking tray 1toward a separation portion comprised of a feeding roller 3 a and afriction separation pad 3 b, in which the pickup roller 2 and theseparation portion serves to separate an original document placedtopmost of the bunch of original documents in a sheet by sheet mannerand conveys the original document to a pair of primary register rollers4 a, 4 b. The pair of primary register roller 4 a, 4 b is ceased whenthe front tip of the original document has reached the pair, and then,after a loop is formed by the conveying of the feeding roller 3 a and aslant correction is performed, the original document is passed over atop surface of a C-guide 16, and is conveyed to an original documentconveying portion C serving as a conveying means.

In respect of the original document conveying portion C, the originaldocument conveyed from the original document feeding portion Bis thenconveyed with a prescribed speed between the small platen glass 8 and awhite panel 9 by a lead roller 6, a secondary register roller 5, aprimary leading roll 7, and a secondary lead roll 12. During thisprocess, the exposure apparatus 103 is stationed at a prescribedposition on the small platen glass, that is, below the reading positione, so as to perform exposure.

During the exposure, the tip of the original document is guided at abottom surface of the C-guide 16, and is guided to a nipping portion ofa pair of reverse-discharge rollers 13 a, 13 b serving as a pair ofreverse-discharge rotating members for a original document dischargeportion D.

In respect of the original document discharge portion D, the pair ofreverse-discharge rollers 13 a, 13 b are separated during the exposureperformed at the reading position e, nevertheless, after the rear edgeof the original document has passed the reading portion e and thereading process is completed, the reverse-discharge roller 13 b movesupward, the reverse-discharge roller 13 a and reverse-discharge roller13 b nips the original document, and the original document showing abackside of the original document is discharged upon a discharge tray 14of a discharge stacking portion E.

(Reading of Double-sided Original Document)

Next, an embodiment of a structure for conveying a double-sided originaldocument will be described. First, the original document stacked on theoriginal document stacking portion A is separated sheet by sheet by theoriginal document feeding portion Band is conveyed to the originaldocument conveying portion C. In the same manner as the aforementionedone-side reading at the original document conveying portion C, theoriginal document is conveyed with a prescribed speed between the smallplaten glass 8 and a white panel 9 in a direction of the originaldocument discharge portion D. During this process, the exposureapparatus 103 is stationed below the reading position e so as to performexposure for the first side of the original document.

In respect of the original document discharge portion D, the originaldocument is guided to a primary conveying path R1, and when the rearedge of the original document passes a position of reverse-dischargesensor S1, the pair of reverse-discharge rollers 13 a, 13 b are reversedby the signal from the reverse-discharge sensor S1 having detected thepassing of the original document. Subsequently, owing to the work of thea flapper 20, the original document is guided to a secondary conveyingpath R2, and the original document is switched back and conveyed to thesecondary register roller 5 of the original document conveying portion Cbeing positioned in an opposite direction of the discharging direction.In this process, the secondary register roller 5 is ceased when thefront tip of the original document has reached the secondary registerroller 5, and then, after a loop is formed by the driving of the pair ofreverse-discharge rollers 13 a, 13 b and a slant correction isperformed, the original document is conveyed to the original documentconveying portion C. At the original document conveying portion C, inthe same manner as the first surface, exposure upon the second surfaceis performed and the original document is again conveyed to the originaldocument discharge portion D.

In respect of the original document discharge portion D, owing to thestructure of the original document processing apparatus 101 of thisembodiment, the original document would be in a face-up manner after thesecond surface has been read and would cause disarrangement in the orderof discharged original documents; subsequently, the reversal would berequired to be performed again.

Accordingly, in respect of the original document discharge portion D,when the rear edge of the original document passes the position of thereverse-discharge sensor S1, the pair of reverse-discharge rollers 13 a,13 b are reversed by the signal from the reverse-discharge sensor S1having detected the passing of the original document, and the originaldocument is again conveyed in the direction of the original documentconveying portion C. In such process, since only a reversal of theoriginal document surface is performed for enabling the originaldocument to be discharged with the backside of the original documentfacing upward, the secondary register roller 5 does not perform slantcorrection.

The original document having passed the original document conveyingportion Cis thrice conveyed to the original document discharging D, andthe pair of the reverse-discharge rollers 13 a, 13 b nips the originaldocument, and the original document showing a backside is dischargedupon a discharge tray 14 of a discharge stacking portion E.

(Drive Control for Reverse-Discharge Roller)

Next, a pair of reverse-discharge rollers for drive control regardingthis embodiment will be explained. As described above, the pair ofreverse-discharge rollers 13 a, 13 b arranged at the original documentdischarge portion D is capable of rotating forward and reverse, andfurther, is structured for being able to attach and separate bysolenoid.

During conveying of a double sided original document, and especiallyduring conveying of an original document having a maximum conveyablelength, the original document processing apparatus 101 is structuredwith a separable pair of reverse-discharge rollers 13 a, 13 b andperforms switchback conveyance where the front edge of the originaldocument and the rear edge of the original document would cross overeach other between the reverse-discharge roller 13 a and thereverse-discharge roller 13 b.

In detail, first, in the process of reading the first surface, the pairof reverse-discharge rollers 13 a, 13 b are separated during the startof the original document reading process. After the image readingprocess of the first surface, in other words, after the rear edge of theoriginal document has passed the reading position e, the pair ofreverse-discharge rollers 13 a, 13 b nips and maintains the originaldocument, and conveys the original document to the original documentdischarge portion D in a nipping manner.

Then, after the rear edge of the original document passes thereverse-discharge sensor, the pair of reverse-discharge rollers 13 a, 13b are driven in reverse in a direction toward the original documentconveying portion C by the signal from the reverse-discharge sensor S1having detected the passing of the original document, and a switchbackconveyance of the original document toward the original documentconveying portion C is performed owing to the work of the flapper 20.

After the original document is delivered to the original documentconveying portion C, in other words, after the original document isnipped and conveyed to the lead roller 6 and the secondary registerroller 5, the pair of reverse-discharge rollers 13 a, 13 b wouldseparate and cease driving. Although the reading procedure of the secondsurface is performed at the original document conveying portion C, thepair of reverse-discharge rollers 13 a, 13 b would maintain the cease ofdriving during the reading process.

Then, at the time when the rear edge of the switchback conveyed originaldocument has been released from the pair of reverse-discharge rollers 13a, 13 b, the pair of reverse-discharge rollers 13 a, 13 b would startdriving toward the original document discharging direction, and wouldattach to each other so as to nip and convey the original document.

In the same manner, in means to discharge the original document in aface-down manner, the reversing process is repeated once more, and then,the original document is discharged to the discharge stacking portion E.

Accordingly, in the foregoing switchback conveying process, since thepair of reverse-discharge rollers 13 a, 13 b would cease driving untilthe original document conveyed by the lead roller 6 is released from thepair of reverse-discharge rollers 13 a, 13 b, the lead roller 6 and thepair of reverse-discharge rollers 13 a, 13 b would not pull the originaldocument from each other. Therefore, an increase of conveying load couldbe prevented and a size reduction of a motor could be allowed.

(Structure for Electricity Removal)

Next, a structural arrangement of an electricity removal means forremoving electricity of the discharged original document will beexplained.

As described above, during conveying of an original document having amaximum conveyable length, the original document processing apparatus101 is structured with a separable pair of reverse-discharge rollers 13a, 13 b and performs switchback conveyance where the front edge of theoriginal document and the rear edge of the original document cross overeach other at the original document discharge portion D. Then, thedischarge original document is contacted with a electricity removingneedle 17 serving as a electricity removing means; this results to aremoval of electricity of the original document and an improvement instacking performance.

The electricity removal needle 17 of this embodiment is arranged in aposition shown in FIG. 3. The following structure is selected so as toavoid stacking trouble where the front edge of the original documentwould not contact with the electricity removal needle 17 when crossingover during the switchback conveyance process, and to avoid troublewhere the original document is electrified due to lack of electricityremoval. In other words, the position of the electricity removal needle17 is to be specified. In a case where the distance between theelectricity removal needle 17 and the pair of reverse-discharge rollers13 a, 13 b is L1, the distance between the pair of reverse-dischargerollers 13 a, 13 b and the secondary register roller 5 on the leadroller 6 is L2, the distance between the secondary register roller 5 andthe primary register roll 7 is L3, the distance between the primary leadroll 7 and the secondary lead roll 12 is L4, and the distance betweenthe secondary lead roll 12 and the pair of reverse-discharge rollers 13a, 13 b is L5, the cross over position of the front edge and the readedge would be defined at an upstream side of the electricity removalneedle 17, and the electricity removal needle 17 would be arrangeddownstream in the sheet discharging direction from the cross overposition of the original document, by means of setting the length of aswitchback conveyance path (L1, L2, L3, L4, L5) in relation with amaximum original document length L into L<2L1+L2+L3+L4+L5. In otherwords, by adjusting the total length of the switchback conveyance path,the cross over position of the front edge and the rear edge whenconveying a original document of maximum original document length wouldbe defined to be positioned between the electricity removal needle 17and the pair of reverse-discharge rollers 13 a, 13 b.

Accordingly, when the electricity removal needle 17 contacts the frontedge of the conveyed original document, the rear edge of the originaldocument would not cover such contacting portion, and the entiredischarged original document could securely contact the electricityremoval needle 17 and remove electricity, and stacking performance couldbe improved.

It is now to be noted that in order to securely remove electricity whenconveying an original document of a small size, an electricity removalneedle 18 serving as a second electricity removal means could bedisposed between the electricity removal needle 17 and the pair ofreverse-discharge rollers 13 a, 13 b.

In FIG. 4, another embodiment of this invention regarding an originaldocument processing apparatus is shown. Although the electricity removalneedle 17 in the aforementioned embodiment is arranged above theoriginal document, the electricity removal needle 17 for this embodimentis arranged below the original document. It is now to be noted that alsoin this embodiment, the front edge of the original document would notoverlap with the rear edge and a state of no electricity removal for theentire original document could be prevented, by disposing theelectricity removal needle 17 downstream in the sheet dischargingdirection from the cross over position of the front edge and the rearedge of the original document.

Although an original document processing apparatus is given as anexample of a sheet conveying apparatus in the foregoing embodiment, itshould now be noted that a sheet conveying apparatus being a recordingapparatus capable of double-side printing could also be used byarranging a recording means such as a recording head, instead of areading means.

Since this invention is thus structured, removal of electricity for adischarged original document could steadily be performed and stackingperformance could be improved by means of feeding a sheet of a maximumconveyable length to a conveying means from a pair of reverse-dischargerotating members by switchback, and arranging an electricity removalmeans for removing electricity at a position nearer toward the sheetdischarging direction than the cross over position of the front edge andthe rear edge of the original document when being discharged afterpassing a prescribed position and passing the pair of reverse-dischargerotating members again.

What is claimed is:
 1. A sheet conveying apparatus comprising: conveyingmeans for conveying a sheet to a prescribed position; a pair ofreverse-discharge rotating members capable of rotating forward andreverse for feeding the sheet to said conveying means by switchback, anddischarging the sheet conveyed from said conveying means; andelectricity removal means for removing electricity from the conveyedsheet; wherein the switchback serves to feed a sheet from said pair ofreverse-discharge rotating members to said conveying means; and whereinsaid electricity removal means is disposed at a downstream side in asheet discharging direction from a cross over position for a front edgeof the sheet and a rear edge of the sheet in a case of conveying thesheet having maximum conveyable length by switchback, and at adownstream side in the sheet discharging direction of said pair ofreverse-discharge rotating members.
 2. The sheet conveying apparatusaccording to claim 1, wherein said electricity removal means and saidpair of reverse-discharge rotating members have a secondary electricityremoval means disposed therebetween.
 3. The sheet conveying apparatusaccording to claim 1 or claim 2, wherein said electricity removal meansis disposed above the conveyed sheet.
 4. The sheet conveying apparatusaccording to claim 1 or claim 2, wherein said electricity removal meansis disposed below the conveyed sheet.
 5. An image reading apparatus forconveying a sheet and for reading an image written on the sheet, theimage reading apparatus comprising: the sheet conveying apparatusdescribed in any one of claim 1 or claim 2; and a reading means forreading an image at the prescribed position of the sheet conveyingapparatus.
 6. An original document processing apparatus comprising:conveying means for conveying an original document to an originaldocument reading position; a pair of reverse-discharge rotating memberscapable of rotating forward and reverse for feeding the originaldocument to said conveying means by switchback, and discharging theoriginal document conveyed from said conveying means; and electricityremoval means for removing electricity from the conveyed sheet; whereinthe switchback serves to feed an original document from said pair ofreverse-discharge rotating members to the conveying means; and whereinthe electricity removal means is disposed at a downstream side in anoriginal document discharging direction from a cross over position for afront edge of the original document and a rear edge of the originaldocument in a case of conveying the original document having a maximumconveyable length by switcbback, and at a downstream side in theoriginal document discharging direction of said pair ofreverse-discharge rotating members and a back edge of said originaldocument, when said original document is passed through said originaldocument reading position in an upside-down manner, in a case where saidoriginal document subject of being conveyed by said original documentprocessing apparatus of a maximum conveyable length.
 7. The originaldocument processing apparatus according to claim 6, wherein a distanceof starting from said pair of reverse-discharge rotating members,passing said original document reading position, and returning back tosaid pair of reverse-discharge rotating members is made shorter than themaximum conveyable length; and wherein the cross over position isdisposed between said reverse-discharge rotating members and saidelectricity removal means.
 8. A sheet conveying apparatus comprising:conveyor for conveying a sheet to a prescribed position; a pair ofreverse-discharge rotating members capable of rotating forward andreverse for feeding the sheet to said conveyor by switchback, anddischarging the sheet conveyed from said conveyor; and electricityremoval unit for removing electricity from the conveyed sheet; whereinthe switchback serves to feed a sheet from said pair ofreverse-discharge rotating members to said conveyor; and wherein saidelectricity removal unit is arranged disposed at a downstream side in asheet discharging direction from a cross over position for a front edgeof the sheet and a rear edge of the sheet in a case of conveying thesheet having maximum conveyable length by switchback, and at adownstream side in the sheet discharging direction of said pair ofreverse-discharge rotating members.
 9. The sheet conveying apparatusaccording to claim 8, wherein said electricity removal unit and saidpair of reverse-discharge rotating members have a secondary electricityremoval unit disposed therebetween.
 10. The sheet conveying apparatusaccording to claim 8 or claim 9, wherein said electricity removal unitis disposed above the conveyed sheet.
 11. The sheet conveying apparatusaccording to claim 8 or 9, wherein said electricity removal unit isdisposed below the conveyed sheet.
 12. An image reading apparatus forconveying a sheet and for reading an image written on the sheet, theimage reading apparatus comprising: the sheet conveying apparatusdescribed in any one of claim 8 or 9; and reading means for reading animage at the prescribed position of the sheet conveying apparatus. 13.An original document processing apparatus comprising: a conveyor forconveying an original document to an original document reading position;a pair of reverse-discharge rotating members capable of rotating forwardand reverse for feeding the original document to said conveyor byswitchback, and discharging the original document conveyed from saidconveyor; and electricity removal unit for removing electricity from theconveyed sheet; wherein the switchback serves to feed on originaldocument from said pair of reverse-discharge rotating members to saidconveyor; and wherein said electricity removal unit is disposed at adownstream side in an original document discharging direction from across over position for a front edge of the original document and a rearedge of the original document in a case of conveying the originaldocument having a maximum conveyable length by switchback, and at adownstream side in the original document discharging direction of saidpair of reverse-discharge rotating members.
 14. The original documentprocessing apparatus according to claim 13, wherein a distance ofstarting from said pair of reverse-discharge rotating members, passingsaid original document reading position, and returning back to said pairof reverse-discharge rotating members is made shorter than the maximumconveyable length; and wherein said cross over position is disposedbetween said pair of reverse-discharge rotating members and saidelectricity removal unit.